Re: [PATCH for-4.6] xenstored: log tdb message via xenstored's logging mechanisms

[Ian Campbell <Ian.Campbell@citrix.com>]

ping.

On Mon, 2014-12-15 at 13:18 +0000, Ian Campbell wrote:
> TDB provides us with a callback for this purpose. Use it in both
> xenstored and xs_tdb_dump.
> 
> While at it make the existing log() macro tollerate memory failures.
> 
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> ---
>  tools/xenstore/xenstored_core.c |   39 +++++++++++++++++++++++++++++++++------
>  tools/xenstore/xs_tdb_dump.c    |   12 +++++++++++-
>  2 files changed, 44 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
> index 4eaff57..3fd9a20 100644
> --- a/tools/xenstore/xenstored_core.c
> +++ b/tools/xenstore/xenstored_core.c
> @@ -89,9 +89,14 @@ static void check_store(void);
>  #define log(...)							\
>  	do {								\
>  		char *s = talloc_asprintf(NULL, __VA_ARGS__);		\
> -		trace("%s\n", s);					\
> -		syslog(LOG_ERR, "%s",  s);				\
> -		talloc_free(s);						\
> +		if (s) {						\
> +			trace("%s\n", s);				\
> +			syslog(LOG_ERR, "%s",  s);			\
> +			talloc_free(s);					\
> +		} else {						\
> +			trace("talloc failure during logging\n");	\
> +			syslog(LOG_ERR, "talloc failure during logging\n"); \
> +		}							\
>  	} while (0)
>  
> 
> @@ -1479,13 +1484,35 @@ static void manual_node(const char *name, const char *child)
>  	talloc_free(node);
>  }
>  
> +static void tdb_logger(TDB_CONTEXT *tdb, int level, const char * fmt, ...)
> +{
> +	va_list ap;
> +	char *s;
> +
> +	va_start(ap, fmt);
> +	s = talloc_vasprintf(NULL, fmt, ap);
> +	va_end(ap);
> +
> +	if (s) {
> +		trace("TDB: %s\n", s);
> +		syslog(LOG_ERR, "TDB: %s",  s);
> +		if (verbose)
> +			xprintf("TDB: %s", s);
> +		talloc_free(s);
> +	} else {
> +		trace("talloc failure during logging\n");
> +		syslog(LOG_ERR, "talloc failure during logging\n");
> +	}
> +}
> +
>  static void setup_structure(void)
>  {
>  	char *tdbname;
>  	tdbname = talloc_strdup(talloc_autofree_context(), xs_daemon_tdb());
>  
>  	if (!(tdb_flags & TDB_INTERNAL))
> -		tdb_ctx = tdb_open(tdbname, 0, tdb_flags, O_RDWR, 0);
> +		tdb_ctx = tdb_open_ex(tdbname, 0, tdb_flags, O_RDWR, 0,
> +				      &tdb_logger, NULL);
>  
>  	if (tdb_ctx) {
>  		/* XXX When we make xenstored able to restart, this will have
> @@ -1516,8 +1543,8 @@ static void setup_structure(void)
>  		talloc_free(tlocal);
>  	}
>  	else {
> -		tdb_ctx = tdb_open(tdbname, 7919, tdb_flags, O_RDWR|O_CREAT,
> -				   0640);
> +		tdb_ctx = tdb_open_ex(tdbname, 7919, tdb_flags, O_RDWR|O_CREAT,
> +				      0640, &tdb_logger, NULL);
>  		if (!tdb_ctx)
>  			barf_perror("Could not create tdb file %s", tdbname);
>  
> diff --git a/tools/xenstore/xs_tdb_dump.c b/tools/xenstore/xs_tdb_dump.c
> index b91cdef..7a034c0 100644
> --- a/tools/xenstore/xs_tdb_dump.c
> +++ b/tools/xenstore/xs_tdb_dump.c
> @@ -33,6 +33,15 @@ static char perm_to_char(enum xs_perm_type perm)
>  		'?';
>  }
>  
> +static void tdb_logger(TDB_CONTEXT *tdb, int level, const char * fmt, ...)
> +{
> +	va_list ap;
> +
> +	va_start(ap, fmt);
> +	vfprintf(stderr, fmt, ap);
> +	va_end(ap);
> +}
> +
>  int main(int argc, char *argv[])
>  {
>  	TDB_DATA key;
> @@ -41,7 +50,8 @@ int main(int argc, char *argv[])
>  	if (argc != 2)
>  		barf("Usage: xs_tdb_dump <tdbfile>");
>  
> -	tdb = tdb_open(talloc_strdup(NULL, argv[1]), 0, 0, O_RDONLY, 0);
> +	tdb = tdb_open_ex(talloc_strdup(NULL, argv[1]), 0, 0, O_RDONLY, 0,
> +			  tdb_logger, NULL);
>  	if (!tdb)
>  		barf_perror("Could not open %s", argv[1]);
>